1. Field of the Invention
The present invention relates to a semiconductor circuit that performs certain signal processing on an input signal.
2. Description of the Related Art
Signal processing circuits, which perform certain signal processing on an input signal to provide a change to a characteristic value of the signal, for example, phase, amplitude and frequency characteristic, and output the signal thus changed, are widely used for various semiconductor circuits (hereinafter, referred to as ICs). Examples of such signal processing circuits include a delay circuit, amplifier, filter, and the like.
An amount of change provided to a characteristic value of a signal by the above signal processing circuit is sometimes dependent on a power supply voltage. For example, it is known that a delay amount of a delay circuit configured with multi-stage cascaded buffers (inverters) is affected by a power supply voltage. If a power supply voltage for such a signal processing circuit is generated by a switching power supply, an amount of change provided to a characteristic value of a signal varies due to the influence of a ripple of the power supply voltage. That is, there are problems that, in the case of a delay circuit, jitter is superimposed on a delay amount; and in the case of an amplifier, a ripple is superimposed on an amplitude of a signal.